Electric discharge tube



1950 s. G. OHLUND 2,518,248

ELECTRIC DISCHARGE TUBE Filed Oct. '7, 1948 Patented Aug. 8, 1950 UNITED STATES PATENT OFFICE ELECTRIC DISCHARGE TUBE Application October 7, 1948, Serial No. 53,359

In Sweden March 20, 1945 1 Claim. (Cl. 176122) This invention relates to a fluorescent electric discharge tube capped at one end of the tube envelope and having two preheatable electrodes disposed, one close to the capped end and the other close to the top end, respectively of the tube envelope. The electrodes are carried by a common stem having a tubular extension in the middle of the tube envelope enclosing connectors to the top electrode.

An object of the invention is to conceal the inner parts of the discharge tube when radiating. For this purpose fluorescent coatings are provided within the tube envelope as well as on the tubular extension, said coatings participating in the transformation of the radiation produced by the discharge and thus making the interior of the tube invisible and without shaded contours. To further promote a homogeneously radiating surface of the tube and prevent blackening of the fluorescent coating on the top of the tube, the top electrode is shielded from said tube end by a sputtering projector facing this tube end.

To carry the electrodes of a discharge tube by a common support is already known in itself; but in discharge tubes for lighting purposes this construction has only been used in connection with discharge tubes with comparatively intensely shining surface, and therefore any inconvenient eflect from this construction of the electrode system is not experienced. Carrying of the electrodes by the common support is, moreover, effected outside the discharge vessel proper, which in its turn is arranged in a surrounding protective envelope. In discharge tubes for lighting purposes with less intensely shining surface and with the electrode carryingdevices arranged in the discharge vessel proper the electrode system would cause a disturbing effect with regard to the emission of light and in many cases render impossible the practical use of the tube. By designing the tube according to this invention the electrode system can be hidden without difliculty and a very advantageous source of light can be obtained. As compared with hitherto commonly used vapour lamps, which are equipped with sockets at both ends of the tube,.it i now possible to obtain a single-socket discharge tube, which is decorative and suitable in many respects.

The invention is illustrated by a type of design shown in the accompanying drawing, and turther to the description of this tube, additional characteristic details and objects or the invention will be given.

The discharge tube as shown consists of a tubulcr envelop ,Lmelted together at one end, the th.! and being closed by item I. Intothll Item 3 are sealed the connectors 4 for the lower elec trode 2 and the connector 6 for the upper electrode I I. In order to extend the discharge path as much as possible over the discharge tube, the connectors l are suitably bent down so that the lower electrode 2 is close to the bottom of the tube, and the connectors 6 are so long that the upper electrode H is close to the tube top. The inside of the tube is covered with a fluorescent coating 8. The connectors 6 to the upper electrode are surrounded by a glass tube 5 slid over these connectors, which at the lower end is sealed to the stem 3 and at the upper end forms a pinch l0. On the glass tube 5 a fluorescent layer is applied. The upper electrode is covered by a sputtering protector l3 in the shape of a hood or the like, carried by a supporting wire l2 from pinch 10 of glass tube 5. The sputtering protector prevents the top of glass cover I from being blacked by material disintegrated from electrode II. A similar protector may also be arranged at the lower electrode. For attaching the lamp in a holder, the lower end is fitted with a socket l. in which a glow relay or similar auxiliary device for lighting the vapour lamp may be arranged.

What I claim is:

A fluorescent electric discharge lamp comprising a tubular candle-like envelope integrally closed at one end and capped at the opposite end by a mounting socket, two preheatable electrodes in said envelope, one adjacent to each end there of,- said electrodes being carried by a common stem having a tubular extension extending to a place adjacent to the closed end of the envelope. said extension enclosing conductors for the electrode at the closed end of the envelope, said closed end being protected by a shield disposed between said closed end and the adjacent electrode, and the inside of said envelope inclusive of the closed end thereof as well as said tubular extension be s provided with fluorescent coatings for concealing the contained parts of the lamp while radiating.

SELFRID GUNNAR CJHLUND.

REFERENCES crrnn The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 2,008,086 Ende July 16, 1935 2,182,732 Meyer Dec. 5, 1939 2,201,390 Delane May 21, 1940 2,411,510 Abadie Nov. 26. 1946 c -nuIcI-II 

